Field of Invention
The present invention relates to a method and a device system for producing ethylene glycol through industrial synthesis gas, in particular to a method and a device system for producing dimethyl oxalate through high-pressure carbonylation of industrial synthesis gas and producing ethylene glycol through dimethyl oxalate hydrogenation.
Description of Related Arts
Ethylene glycol is a chemical which is widely used, is mainly applied in various production fields of polyester fibers (PET), anti-freezing agents, ethanolamine, explosives, etc., and is used in a great amount as solvent, lubricant and plasticizer. The application proportion of ethylene glycol in the PET polyester industry is close to 95%. At present, ethylene glycol is produced in industry mainly by adopting a route of producing ethylene oxide through gas phase oxidation of petro-ethylene and then producing ethylene glycol through liquid phase catalytic hydration. However, since the international oil price is kept high for a long time in recent years, the industrial link of producing ethylene glycol by using ethylene as raw materials faces to a great pressure at present. Thus, a technical route of producing ethylene glycol by adopting synthesis gas is increasingly and widely concerned due to low production cost.
At present, a tubular reactor is mainly adopted in a method for producing ethylene glycol by using coal. However, there are common problems of low reaction heat transfer efficiency, low utilization coefficient and low packing coefficient of catalyst, such that the production capability of the reactor is influenced.
Patent (Publication No.: CN101462961) provides a method for producing ethylene glycol and coproducing dimethyl carbonate. This method comprises synthesizing dimethyl oxalate and dimethyl carbonate through CO and methyl nitrite, performing distillation separation to obtain dimethyl carbonate products and synthesizing ethylene glycol through catalytic hydrogenation of heavy components dimethyl oxalate, and further comprises performing regeneration reaction of methyl nitrite in the system. However, since a tubular reactor is used as a reactor, waste gas and waste liquid produced during reaction are not recycled and recovered, the energy consumption of the device is relatively high and the increasing national environmental protection requirements cannot be satisfied.
Patent (Publication No.: CN101830806) discloses a method and a device for coproducing dimethyl carbonate and dimethyl oxalate. In the patent, two carbonylation reactors are adopted, the first reactor is a dimethyl carbonate synthesis reactor, the second reactor is a dimethyl oxalate reactor, methyl nitrite produced through reaction respectively enters the two reactors to respectively produce dimethyl carbonate and dimethyl oxalate, and then the products are respectively separated and purified. To view from the angle of the method route design, it substantively involves simple accumulation of two types of reactors and the actual effect of coproducing DMO and DMC in the same device cannot be actually realized. In the patent, energy optimization is not performed to the overall method flow and environmental protection measures which are necessary to be taken during reaction are not disclosed, either. The method is just an experimental method instead of an industrialized method.
Moreover, the loss of NO in the exhaust process and the production of nitric acid byproducts in the treatment reaction method are tough problems. Patent CN201210531022.1 discloses a method, in which the produced nitric acid is concentrated, and then part of NO-containing recycled gas is used to react therewith to produce NO2 which is returned back to the methyl nitrite regeneration reactor. However, the NO-containing recycled gas further contains a great amount of gases such as methyl nitrite and methanol which will also react with the concentrated nitric acid, such that the products are complex and the efficiency of the device is influenced.
To sum up, the existing method for producing ethylene glycol by using coal mainly has the problems that the catalyst utilization rate is low, the catalyst packing coefficient is low, the valuable gases in the device cannot be fully utilized but pollute the environment, the heat of the device system cannot be fully utilized and thereby the social and economic benefits are not ideal.